ATP、二价金属离子和pH对鸡肝甲羟戊酸5-二磷酸脱羧酶的动力学影响。

Kinetic effects of ATP, divalent metal ions and pH on chicken liver mevalonate 5-diphosphate decarboxylase.

作者信息

Jabalquinto A M, Cardemil E

机构信息

Departamento de Química, Facultad de Ciencia, Universidad de Santiago de Chile.

出版信息

Biochim Biophys Acta. 1987 Nov 26;916(2):172-8. doi: 10.1016/0167-4838(87)90105-1.

DOI:10.1016/0167-4838(87)90105-1

PMID:3676328

Abstract

The activity of chicken liver mevalonate 5-diphosphate decarboxylase was measured over a wide range of Mg2+ and ATP concentrations. It was found that free ATP activated the enzyme, whereas free Mg2+ had no effect on the enzyme activity. Computed analyses of free species concentrations and pH studies indicated that MgATP2- is the true substrate. The relative efficiencies of Mg2+, Mn2+, Cd2+, and Zn2+ as activating metal ions were evaluated in terms of V/Km for the corresponding (metal-ATP)2- complexes, and the relative ratios were: Mn2+ 100, Cd2+ 37, Mg2+ 14, Zn2+ 1.7. Inhibitory effects were demonstrated for all free divalent cations tested, except for Mg2+, and were in the order Zn2+ greater than Cd2+ greater than Mn2+.

摘要

在广泛的Mg2+和ATP浓度范围内测定了鸡肝甲羟戊酸5-二磷酸脱羧酶的活性。发现游离ATP激活该酶，而游离Mg2+对酶活性无影响。游离物种浓度的计算分析和pH研究表明，MgATP2-是真正的底物。根据相应（金属-ATP）2-复合物的V/Km评估了Mg2+、Mn2+、Cd2+和Zn2+作为激活金属离子的相对效率，相对比率为：Mn2+ 100、Cd2+ 37、Mg2+ 14、Zn2+ 1.7。除Mg2+外，所有测试的游离二价阳离子均表现出抑制作用，且抑制顺序为Zn2+＞Cd2+＞Mn2+。